Model 4124 - 4:1 Tuner Balun 1 - 45 MHz 5kW

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4124 - 1
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Jerry Sevick (W2FMI) specifically researched and designed this tuner balun to provide a very constant 50 ohm input impedance on the lower frequencies where most baluns can drop by 20-40%.  In addition, the Thermaleze wire/Teflon tube windings on a large iron powder core allow the balun to handle large swings in impedance and high temperatures with ease.  It can be used internally or externally making it the perfect replacement/upgrade alternative for the 4:1 balun in any tuner. This unit utilizes a voltage winding which is what 99% of all tuners incorporate as they provide very good transformation with virtually no chance of saturation.

All of these features make the unit very unique and rugged while being especially effective on the low bands and can provide enhanced matching capability where other baluns fall short. If you have a tuner with a bad balun or a homebrew tuner in need of an excellent 4:1 balun, this is the perfect model. The design is extremely rugged, almost immune to heat and can handle the full HF frequency spectrum. The model 4124x has no enclosure or connectors and is intended as a replacement balun for most tuners with medium to large internal dimensions. 

Balun Designs offers this unique balun using a three inch double height core. This larger size provides the necessary increase in inductance for enhanced performance on the low bands while maintaining the same wide bandwidth through 31MHz and above.  Dr. Sevick's research showed that, when used with a balanced antenna, this balun exhibits characteristic current balance normally found only in a current winding.  Excellent for use with doublets, extended Zepps, large skyloops and is a good replacement balun for Super Loops.

Please review the impedance curves in the graph below to better understand the efficiency and response of this balun.

Click to Enlarge



  Core Material   Large 3" DOUBLE HEIGHT iron powder toroid for excellent low frequency performance.
  Core is coated and sealed for long term durability.
  Winding Type  Single bifilar wire pair wound as 4:1 tuner balun.
  Winding Material   Heavy gauge polyamideimide Allex 240 Winding Wire
  Windings are inserted into Teflon tubes increasing total breakdown to 10,000 volts.  
  Power Rating   1 to 35 MHz - 5kW, 7kW intermittent.  35 to 54 MHz - 4kW.  
  All ratings based on resonant load. High SWR will reduce power handling ability.
  Useable Frequency   1 to 45 MHz
  Insertion Loss   Less than .02db
  Connectors   SO-239 connectors are silver plated with Teflon insulation.
  Studs and eyebolts are 1/4 inch.
  Alternate connectors and Mounting Options are available in the Accessories section.
  Hardware   All Stainless Steel
  Enclosure Type   NEMA rated 4x marine grade junction box for outdoor installations.
  Cover utilizes integral neoprene gasket for weatherproof integrity.
  Dimensions   4x4x2 inches for main body of unit
  Dimensional Drawing of Standard Enclosure
  Additional Info   Very high efficiency (98-99%). 
  Iron powder core is very tolerant of high temperatures.

Installation Notes